Experimental study of hydraulic cylinder leakage and fault feature extraction based on wavelet packet analysis

Hydraulic cylinder is the actuator in hydraulic system, and its failure directly affects the normal operation of the system. The leakage of hydraulic cylinder is a major failure mode usually caused by failure or damage of the seal, and it should be detected as early as possible to avoid worse breakdowns of system. However, the leakage is difficult to be diagnosed in the early stage, so the basic aim of the paper is to seek out the fault features which could forecast the early leakage of hydraulic cylinder. In this study, inlet and outlet pressure signals and displacement signal of piston rod of hydraulic cylinder have been collected from a special designed test-bed, which simulates different leakage levels of hydraulic cylinder. The result shows that there are five fault features in total can be extracted by wavelet packet analysis to distinguish different levels of the leakage obviously. (C) 2014 Elsevier Ltd, All rights reserved.